1. Field of the Invention
The present invention relates to a rotating machine provided with a stator core having a salient pole.
2. Description of the Related Art
In recent years, there is a demand for further miniaturization of rotating machines, such as a hard disk drive. Under such a situation, in a rotating machine in which data is recorded, for example, magnetically, data is read and written with a magnetic head tracing over a recording disk through a slight gap between the two while the recording disk is being rotated at high speed.
In order to make such a rotating machine small in size, it is required that data is read and written with the gap between the magnetic head and the recording disk being made extremely to be small, for example, to be 10 nm or less. In addition, with the miniaturization of a rotating machine, the track pitch on the recording disk is also made small. For example, Japanese Patent Application Publication No. 2009-303417 discloses a technique in which, in order to deal with the demand for miniaturization of a brushless motor, the magnetic flux flow of a laminated core is improved to reduce a torque ripple, thereby allowing a vibration in the brushless motor to be suppressed.
Herein, if the gap between a recording/reproducing head and the surface of the recording disk is made smaller, the gap remarkably varies due to a slight vibration in the recording/reproducing head, resulting in a remarkable change in the amplitude of an output signal of the recording/reproducing head. If the trace of the recording disk is disturbed or if the amplitude of an output signal of the recording/reproducing head varies, a malfunction in reading/writing the data in a hard disk drive can occur more frequently. In addition, if the track pitch is made small, the possibility that the trace of recording tracks may be disturbed is increased when the recording/reproducing head vibrates due to a vibration. Accordingly, it is desired that a vibration occurring in a rotating machine is suppressed.